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161. [AMPS] Zener screen supplies (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Tue, 17 Apr 2001 14:31:55 +0100
Never tried to measure it. Whole earwigs can crawl past the edge of the blower wheel, but craneflies are reduced to decimal fractions. 73 from Ian G3SEK Editor, 'The VHF/UHF DX Book' 'In Practice' co
/archives//html/Amps/2001-04/msg00392.html (9,272 bytes)

162. [AMPS] Zener screen supplies (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Tue, 17 Apr 2001 21:16:48 +0100
She's a softie. The other 55 million of us can do much worse than her... if sufficiently provoked. 73 from Ian G3SEK Editor, 'The VHF/UHF DX Book' 'In Practice' columnist for RadCom (RSGB) http://www
/archives//html/Amps/2001-04/msg00403.html (9,437 bytes)

163. [AMPS] RF deck cooling (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Sat, 21 Apr 2001 16:45:49 +0100
Blowing into the output compartment is standard practice on many VHF/UHF cavity amps that use "external anode" tubes - but not quite in the way you were thinking of doing it. If you can totally seal
/archives//html/Amps/2001-04/msg00453.html (9,088 bytes)

164. [AMPS] (no subject) (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Sat, 10 Mar 2001 00:09:15 +0000
The power output capabilities are actually very similar - as you'd expect because they are both 1.5kW dissipation tubes. The filament voltage, bias voltage, cathode impedance and drive requirements a
/archives//html/Amps/2001-03/msg00063.html (8,128 bytes)

165. [AMPS] Meter Protection for Drake L7 (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Sat, 10 Mar 2001 21:17:50 +0000
You're asking for two different things: protection against faults, and low errors due to current flowing through the diode in normal operation. Both depend on the voltage drops across the individual
/archives//html/Amps/2001-03/msg00074.html (9,088 bytes)

166. [AMPS] SB-220 Amplifiers and Garage Sales!! (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Tue, 27 Mar 2001 18:41:49 +0100
When this show was playing about two years ago, we went through all this stuff about equivalent series and parallel resistances and reactances: Rs, Rp, Xs, Xp and all their friends and relatives. You
/archives//html/Amps/2001-03/msg00284.html (9,243 bytes)

167. [AMPS] SB-220: Operate/Standby Switch (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Sun, 4 Feb 2001 09:32:20 +0000
The Eimac data sheet says "180 seconds minimum". The exact warmup time is a judgement call, even by Eimac. If you connect a high-resolution DVM across the heater, it acts as its own resistance thermo
/archives//html/Amps/2001-02/msg00099.html (12,943 bytes)

168. [AMPS] Coax as an RF choke?? (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Fri, 9 Feb 2001 23:55:22 +0000
Sure, it works fine. UT141 semi-rigid is OK at these currents, and you do not need a quarter-wave if you wind it into a coil. 73 from Ian G3SEK Editor, 'The VHF/UHF DX Book' 'In Practice' columnist f
/archives//html/Amps/2001-02/msg00204.html (7,759 bytes)

169. [AMPS] Runaway amp (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Tue, 20 Feb 2001 19:59:42 +0000
Good point - and also, how accurately are you measuring the grid and screen voltages? Are you using a DVM or do the voltages only *look* kind-of constant on an analog meter? If you had not said that
/archives//html/Amps/2001-02/msg00277.html (8,609 bytes)

170. [AMPS] runaway amp. (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Fri, 23 Feb 2001 00:28:24 +0000
W0YR will be off the list for a few weeks, so maybe we have to leave it until he can make some more tests. The real puzzle is that the RF output drifts UPwards, which is quite unusual. 73 from Ian G3
/archives//html/Amps/2001-02/msg00304.html (8,523 bytes)

171. [AMPS] k2riw 2m amp! (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Sun, 25 Feb 2001 08:58:08 +0000
... and more IMD. AFAIK, the most complete information on linear operation of 4CX250Bs is the chapter by GW4FRX in 'The VHF/UHF DX Book'. Very briefly: Va 2000V, Vg2 350V, Vg1 about -55V (adjust for
/archives//html/Amps/2001-02/msg00328.html (9,908 bytes)

172. [AMPS] K2RIW Amps (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Sun, 25 Feb 2001 09:01:52 +0000
In class B or C with a lot of drive, you can indeed get that kind of power from a pair of 4CX250Bs - but that's CW, not linear. The practical limit for good linearity is about 500W in strict class AB
/archives//html/Amps/2001-02/msg00329.html (8,402 bytes)

173. [AMPS] K2RIW Amps (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Sun, 25 Feb 2001 19:45:11 +0000
"The linearity was good"... for California. Here in Europe you'd find your coax cut. 73 from Ian G3SEK Editor, 'The VHF/UHF DX Book' 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.com/g
/archives//html/Amps/2001-02/msg00333.html (8,640 bytes)

174. [AMPS] K2RIW Amps (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Mon, 26 Feb 2001 06:42:58 +0000
... or the sincerest form of signal quality report. 73 from Ian G3SEK Editor, 'The VHF/UHF DX Book' 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.com/g3sek -- FAQ on WWW: http://www.co
/archives//html/Amps/2001-02/msg00345.html (9,154 bytes)

175. [AMPS] Output Pulse from ICOM 706 (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Thu, 4 Jan 2001 15:09:59 +0000
They seem to have solved it on the IC-746. That's as far as I can see, on a non-storage scope but with the brightness turned way up to make even a very short spike visible. It's certainly very visibl
/archives//html/Amps/2001-01/msg00133.html (10,435 bytes)

176. [AMPS] Eimac - Care and Feeding of Power Grid Tubes (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Fri, 5 Jan 2001 18:53:38 +0000
Oh no it isn't. That page has been there since 1996. The idea was that the world should volunteer to update C&F at no expense to Eimac. Mistake #1 was to keep the existing chapter structure - but tim
/archives//html/Amps/2001-01/msg00177.html (9,658 bytes)

177. [AMPS] Eimac - Care and Feeding of Power Grid Tubes (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Fri, 5 Jan 2001 19:34:25 +0000
Sadly so. 73 from Ian G3SEK Editor, 'The VHF/UHF DX Book' 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.com/g3sek -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@co
/archives//html/Amps/2001-01/msg00179.html (9,450 bytes)

178. [AMPS] Eimac - Care and Feeding of Power Grid Tubes (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Sun, 7 Jan 2001 00:06:00 +0000
Please don't get sucked into Rich's opportunistic personal attacks against Eimac staff. 73 from Ian G3SEK Editor, 'The VHF/UHF DX Book' 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co
/archives//html/Amps/2001-01/msg00223.html (10,734 bytes)

179. [AMPS] Eimac - Care and Feeding of Power Grid Tubes (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Sun, 7 Jan 2001 10:07:21 +0000
He has now told us all... again. I agree that Eimac <as a company> made a mistake over C&F, and continues to make a mistake in not pulling those pages and re-thinking what needs to be done. But a mis
/archives//html/Amps/2001-01/msg00235.html (11,047 bytes)

180. [AMPS] Output Pulse from ICOM 706 (score: 1)
Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK)
Date: Mon, 15 Jan 2001 14:30:10 +0000
The problem with reviews is that they can only test systematically for *known* aspects of performance. It's much less certain whether they pick up any other defects that are specific to one particula
/archives//html/Amps/2001-01/msg00364.html (11,517 bytes)


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